Number of n X n symmetric binary matrices with every 1 adjacent to another 1 horizontally or vertically.

A140425

Number of n X n symmetric binary matrices with every 1 adjacent to another 1 horizontally or vertically.

Terms

    a(0) =1a(1) =4a(2) =28a(3) =342a(4) =8170a(5) =388316a(6) =35871274a(7) =6434968504

External references